The math and speculating gets you a starting point for buildng the test wings... Then you evaluate the results of the test wings and... build a better wing.

BTW... yuo can do some homebrew "wind tunnel" testing... Refrigerator box on its side (cut a hole in the side of the box and ut a sheet of plexiglass in so you can see), and a box fan pulling air out. Not too good for high speed stuff... but it can give you a clue for the low speed project. If you can borrow a fire stations smoke blower... you can get a 40 mph breeze in the box eazilly.